The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Large industrial high speed rotating equipment such as cooled turbo machinery with high bearing loads, e.g., steam turbines, centrifugal pumps, motors, generators, centrifugal compressors, etc., contain shaft bearings which generate significant heat during operation of the machinery. This is true of machines that utilize antifriction bearings (such as deep groove ball bearings, cylindrical roller bearings, spherical thrust bearings, etc.) or journal bearings (such as plain bearings, lemon bore bearings, tilting pad bearings, etc.).
Particularly, such machinery is typically operated at high rotating speeds, i.e., high RPMs, such that the large bearings utilized therein are unable to ‘self-cool’. Accordingly, separate auxiliary cooling systems designed to cool the bearings are often provided to prevent the bearings from overheating and failing. That is, auxiliary cooling systems that are separate and independent from cooling systems of the machine that are designed to cool the electrical package of the machine (e.g., the rotor and stator, in the case of electrical machines) are provided to cool the bearings. Such auxiliary cooling systems are known to include circulated liquid medium cooling systems such as water-cooled bearing systems where external water is piped through cooling tubes which cools the bearing lubricating oil, and flood lubrication systems where the bearing lubricating oil itself is pumped out, cooled, and pumped back into the bearing.
Although effective, these auxiliary cooling systems required considerable additional support devices and apparatuses, such as pumps, piping, heat exchangers, fans, etc., and other additional structures, which increase the fabrication and operating costs of such rotating equipment and machinery. Furthermore, due to the lesser reliability and integrity of such auxiliary systems, relative to the rotating equipment and turbo machinery they are designed to cool, such auxiliary systems consequently reduce reliability of the respective rotating equipment and turbo machinery.